<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
    <!-- <script src="https://unpkg.com/vue@3/dist/vue.global.js"></script> -->
    <script src="vue.js"></script>
</head>
<body>
    <div id="box">
        {{ 10+20 }}
        {{ myName }}
    </div>
    <script>
        Vue.createApp({
            data() {
                return {
                    myName:"future"
                }
            },
        }).mount("#box")
    </script>
</body>
</html>